The present disclosure relates to a multilayer ceramic capacitor, a board having the same mounted thereon, and a method of manufacturing the same.
Since such a multilayer ceramic capacitor (MLCC) has advantages such as a small size, high capacitance, ease of mounting, or the like, such a multilayer ceramic capacitor may be used as a component in various electronic devices.
For example, the multilayer ceramic capacitor may be used as a chip shaped condenser mounted on printed circuit boards of various electronic products such as a display device, for example, a liquid crystal display (LCD), a plasma display panel (PDP), and the like, as well as including a computer, a personal digital assistant (PDA), and a mobile phone to serve to charge electricity or discharge electricity.
Generally, the multilayer ceramic capacitor may have a structure in which a plurality of dielectric layers and internal electrodes having different polarities between the dielectric layers are alternately disposed.
In this case, since the dielectric layers have piezoelectric properties, when a direct current (DC) voltage or an alternating current (AC) voltage is applied to the multilayer ceramic capacitor, a piezoelectric phenomenon may be generated between the internal electrodes, such that a volume of a ceramic body is expanded and contracted according to a frequency, thereby generating periodic vibrations.
The vibrations are transmitted to a printed circuit board through external electrodes and a solder connecting the external electrodes of the multilayer ceramic capacitor to the printed circuit board, such that the entire printed circuit board becomes a sound reflective surface to generate a vibration sound to be a noise.
In this case, the solder connecting the external electrode and the printed circuit board is inclined from both side surfaces and both end surfaces of the ceramic body along a surface of the external electrode at a predetermined height. As a volume and a height of the solder increase, vibrations of the multilayer ceramic capacitor may be further easily transferred to the printed circuit board, such that vibration sound could be severely generated.
The vibration sound may be in an audible frequency region of 20 to 20,000 Hz, causing listener discomfort, and the vibration sound causing listener discomfort refers to an acoustic noise.
Recently, in electronic devices, since acoustic noise generated in the multilayer ceramic capacitor as described above may be significant due to a decreased noise of components, research into a technology of effectively decreasing the acoustic noise generated in the multilayer ceramic capacitor has been required.
A multilayer ceramic capacitor and a board having the same mounted thereon have been disclosed in the following Patent Document 1, but a structure in which an external electrode includes an insulating layer for decreasing acoustic noise has not been disclosed therein.